6.3 lecture - muscle EMs, cytoskeleton, & embryology Flashcards

1
Q

in smooth muscle, calcium is

A

start

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2
Q

the sarcoplasmic reticulum ends in tubular structures called

A

terminal cisternae

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3
Q

VGCa++ channels in t-tubules

A

DHP dihydropyridine receptors

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4
Q

T/F in all types of muscle, calcium is shuttled into the cell via caveolae and sequestered in the SR until an electrical signal is received

A

true

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5
Q

in addation to actin, dense bodies bind to intermediate filaments, which are typically __ in visceral muscle and __ in vascular muscle

A

desmin in visceral smooth muscle

vimentin in vascular smooth muscle

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6
Q

what are the intermediate filaments in:

  • visceral smooth muscle
  • vascular smooth muscle
A
  • desmin

- vimentin

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7
Q

this intermediate filament connects Z-lines of myofibrils with each other

A

desmin

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8
Q

muscular dystrophy is due to a problem with this protein

A

dystrophin

part of costamere complex that anchors Z lines to sarcolemma

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9
Q

muscular dystrophy is due to a lack of this protein

A

dystrophin

part of costamere complex that anchors Z lines to sarcolemma

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10
Q

myotube

A

early formation with central nuclei and a few peripheral myofibers that will eventually grow into myofibers of adult skeletal muscle

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11
Q

T/F adult myofibers can increase in number

A

false

can only change in size by addition or subtraction of myofibrils

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12
Q

how are muscle external membrane, nerve external membrane, and basement membrane functionally similar?

A

serves as scaffolding for tissue repair

-disruption makes regeneration response more difficult

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13
Q

T/F intermediate filaments seem to have little importance in skeletal muscle

A

true

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14
Q

T/F cardiac and skeletal muscle contain intermediate filaments

A

true

connecting Z-lines and anchoring z-lines to costameres

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15
Q

why is the occasional cardiac myocyte binucleated?

A

failure of division

not a combination to form a functional syncytium as with skeletal muscle

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16
Q

T/F cardiac cells can have multiple nuclei within sarcolemma

A

true

occasionally a failure of division results in binucleated cardiac myocytes

17
Q

what 3 junctions does an intercalated disk consist of?

A
fascia adherens (actin + catenin)
desmosomes (intermediate filament + catenin)
gap junctions
18
Q

other than myocytes, other specialized cardiac cells include

A

cardiac endocrine cell (mostly atrial)

cardiac conducting cell (in myocardial layer)

19
Q

which layer of heart wall has major blood vessels?

A

epicardium

20
Q

how would a type I red muscle fiber compare to a type IIb white muscle fiber on H&E?

A

*not going to be able to tell the difference, need PAS stain
BUT if really pressed to try:
white probably larger
red probably more darkly eosinophilic (more mitochondria)

21
Q

how would a type I red muscle fiber compare to a type IIb white muscle fiber on H&E?

A

white probably larger

red probably more darkly eosinophilic (more mitochondria)

22
Q

chief materials of:
lamina lucida
lamina densa
lamina retucularis

A

lucida - glycoproteins (laminin, fibronectin)
densa - type IV collagen
reticularis - type IV collagen; type VII collagen

23
Q

chief materials of:
lamina lucida
lamina densa
lamina retucularis

A

lucida - glycoproteins (laminin, fibronectin)
densa - type IV collagen
reticularis - type IV collagen; type VII collagen

24
Q

T/F satellite cells are within external membrane of muscle fiber but outside sarcolemma

A

true

but will never be able to make this out on LM

25
Q

quiescent precursors that become activated to divide and differentiate in response to the needs of muscle growth and damage

A
satellite cells
(quiescent but actively monitoring and moving along surface)
26
Q

T/F external membrane is a barrier to neurotransmitter and therefore does not exist in neuromuscular junciton

A

false
not a barrier to NT
exists in NMJ same as everywhere else

27
Q

T/F external membrane is a barrier to neurotransmitter and therefore does not exist in neuromuscular junciton

A

false
not a barrier to NT
exists in NMJ same as everywhere else

28
Q

T/F adipocytes have an external membrane

A

true
muscle cells
nervous cells
adipocytes

29
Q

T/F smooth muscle motor end plates have junctional folds

A

false

at least not as significantly as skeletal muscle

30
Q

T/F smooth muscle motor end plates have junctional folds

A

false

at least not as significantly as skeletal muscle

31
Q

why do muscle spindle and golgi tendon organ include small muscle fibers in addition to nerves?

A

muscle fiber contracts and stretches proportionally to the other fibers so that nerves can sense length in the case of the muscle spindle and force exerted in the case of the golgi tendon organ

32
Q

why do muscle spindle and golgi tendon organ include small muscle fibers in addition to nerves?

A

muscle fiber contracts and stretches proportionally to the other fibers so that nerves can sense length in the case of the muscle spindle and force exerted in the case of the golgi tendon organ

33
Q

muscle spindle is encapsulated by …

A

perimysium (kind of a perineurium too)

34
Q

musculotendinous junction

A

actin filaments directly anchored to cell membrane in structure similar to fascia adherens

35
Q

musculotendinous junction

A

actin filaments directly anchored to cell membrane in structure similar to fascia adherens

36
Q

what does an muscle external membrane directly surround?

A

plasmalemma bound units, including:
-skeletal muscle fibers
-cardiac myocytes
-smooth muscle cells
NOT skeletal muscle fascicles (not directly)
NOT smooth muscle bundles (not directly)
NOT skeletal muscle fibrils (not directly)

37
Q

what does an muscle external membrane directly surround?

A

plasmalemma bound units, including:
-skeletal muscle fibers
-cardiac myocytes
-smooth muscle cells
NOT skeletal muscle fascicles (not directly)
NOT smooth muscle bundles (not directly)
NOT skeletal muscle fibrils (not directly)

38
Q

what will break first, plasmalemma or external membrane?

A

plasmalemma
(external membrane is very tough)
-can have broken plasma membrane but intact external membrane